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MK20DX128VFM5: USB CDC device not enumerating

Question asked by Hui Shao on Sep 25, 2014
Latest reply on Oct 2, 2014 by Hui Shao

Hi-

 

I have problem to make my board enumerated after plugging USB connector into Windows PC. Windows shows nothing after a connection. My configuration is like:

 

OS: MQX 4.1.1

HW: MX20DX128VFM5

Tool: IAR and I-jet

BSP: k20d50m


My costumed board is driven by 8MHz crystal and +5v comes directly from PC USB port. The USB ID detection pin is tied to ground and +5V power is seen on the board after connecting to PC. After calculation my board should supply 48MHz to ARM core.


HW wise, how can I debug this issue? I have also post same question on MQX forum(MQX 4.1: USB CDC device "virtual com" not enumerating).

I am asking here to see if I can get HW people help on it.


Thanks!


Hui

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